antonio-castellon module-auth up to 2.2.x Headers /JWT/OIDC validateToken improper authentication

Summaryinfo

A vulnerability described as critical has been identified in antonio-castellon module-auth up to 2.2.x. This affects the function validateToken of the file /JWT/OIDC of the component Headers Handler. Such manipulation leads to improper authentication. This vulnerability is listed as CVE-2026-58399. The attack may be performed from remote. There is no available exploit. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability was found in antonio-castellon module-auth up to 2.2.x and classified as critical. Affected by this issue is the function validateToken of the file /JWT/OIDC of the component Headers Handler. The manipulation with an unknown input leads to a improper authentication vulnerability. Using CWE to declare the problem leads to CWE-287. When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct. Impacted is confidentiality, integrity, and availability. CVE summarizes:

@acastellon/auth is an authentication control system for microservices. Versions prior to 2.3.0 appear to allow an unauthenticated authentication bypass in validateToken() through spoofable auth-user and Host request headers. The validateToken middleware contains a service-to-service bypass for auth-user: service-brother when req.get('host').startsWith(getHostName()). Both values involved in the check can be influenced by an unauthenticated HTTP client: auth-user is a request header, and Host is also client-controlled. As a result, a remote unauthenticated attacker can send a request with crafted headers and bypass token validation before the normal legacy/JWT/OIDC validation logic runs. A fix has been implemented in v2.3.0.

The advisory is shared for download at github.com. This vulnerability is handled as CVE-2026-58399 since 06/30/2026. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. There are known technical details, but no exploit is available.

Upgrading to version 2.3.0 eliminates this vulnerability.

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Productinfo

Vendor

• antonio-castellon

Name

• module-auth

Version

• 2.0
• 2.1
• 2.2

Website

• Product: https://github.com/antonio-castellon/module-auth/

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